Hot liquid dispenser reverse flow sensor with check valve slider and magnetically operated switch

ABSTRACT

A reverse flow sensor for permitting flow of fluid in one direction while sensing backflow of fluid to actuate circuitry to activate a suitable response in a backflow condition. The reverse flow sensor comprises a housing defining a chamber with a check valve slider in the chamber. A magnet is carried by the slider for movement therewith. The slider has an opening permitting flow of fluid therethrough in one direction and impeding fluid flow in a second direction so that fluid flow toward the second direction acts to move the slider in the second direction. Magnetic responsive means are associated with the housing for reacting to movement of the slider.

United States Patent 1191 1111 3,851,127

Gardner, Jr. et al. Nov. 26, 1974 HOT LIQUID DISPENSER REVERSE FLOW3,200,214 8/1965 Aubert 200/61.86 x 3,507,359 4/1970 Warnock 200 81.9 Mux 3,551,620 12/1970 Hoover 200/81.9 M ux SWITCH 3,608,472 9/1971Pelster et al. 200/81.9 M x [75] Inventors: John A. Gardner, Jr.,Tewksbury;

Merle S. Brown, Cohasset, both of Primary ExamineFJames R. Scott MassAttorney, Agent, or FirmWolf, Greenfield & Sachs [73] Assignee: Jet-Spray Cooler, lnc., Waltham,

Mass.

22 Filed: Aug. 9, 1973 [57] ABSTRACT [2]] Appl. No.: 387,004 A reverseflow sensor for permitting flow of fluid in Related U S Application Dataone direction while sensing backflow of fluid to actuate circuitry toactivate a suitable response in a backflow condition. The reverse flowsensor comprises a housing defining a chamberwith a check valve sliderin the chamber. A magnet is carried by the slider for movementtherewith. The slider has an opening per- S 200/6186 200/8L9 mittingflow of fluid therethrough in one direction and [58] Field of Search200/61 86 81 9 R 81 9 M impeding fluid flow in a second direction sothat fluid R 82 4 f. flow toward the second direction acts to move the137/625 25 5'1 625 slider in the second direction. Magnetic responsive130 318 324 325 349 351 353 333 334 means are associated with thehousing for reacting to movement of the slider.

[60] Division of Ser. No. 177,597, Sept. 3, 1971, Pat. No. 3,790,028,which is a continuation-in-part of Ser. No. 887,671, Dec. 23, 1969,abandoned.

[56] References Cited 4 c1 13 n F UNITED STATES PATENTS raw'ng 3,l74,5l93/1965 Pizzurro et al 251/353 X 'l V e lllllllz f.

PATENIEL REV 26 I974 SHEET 10F 8 -FIG.4

PATENTEL NOV 2 8 I974 FIG. 6

SHEEI 5 BF 8 ZIIIIIIIIIZ HOT LIQUID DISPENSER REVERSE FLOW SENSOR WITHCHECK VALVE SLIDER AND MAGNETICALLY OPERATED SWITCH RELATED APPLICATIONThis application is a division of copending U.S. application Ser. No.177,597 filed Sept. 3, 1971 now issued as U.S. Pat. No. 3,790,028 datedFeb. 5, 1974, which is a continuation-in-part of U.S. application Ser.No. 887,671 filed Dec. 23, 1969 and now abandoned.

This invention relates to beverage dispensers and more particularlycomprises a new and improved dispenser for hot chocolate or other liquidfood made up of a combination of two liquid parts. The invention alsoAnother object of this invention is to'provide a hot reverse flow sensorwhich is highly accurate, reliable,

relates to a sensor for monitoring flow and sensing unacceptablebackflow of fluids. The sensor is particularly useful when incorporatedin a beverage dispenser to sense an out-of-syrup condition.

Most beverage dispensers handling hot chocolate now available include ahot water tank, a syrup or powder container of ready-to-mix concentrate,a flow metering system to control the flow rate of water andconcentrate, and a programmer for controlling the size of the drink. Allof the machines heretofore available have deficiencies in one or more ofthe standards established to measure acceptability. These standardsinclude simplicity of operation, reliability, cleanability, accuracy ofmetering, ease of portion control, and speed of operation. For example,in all hot chocolate dispensers known to applicant, in order to cleanthe machine it is necessary to disassemble much of the flavor circuitand submerge the parts in a sanitizing solution in order to meet thestandards of cleanliness imposed by federal, state and local healthagencies. The hot chocolate dispensers which use powder concentrate donot precisely meter the mixture of water and powder, and are not capableof accurately preserving the ratio of powder to water when dispensingportions of different sizes. And all of the prior art hot chocolatedispensers known to applicant have a time cycle which varies with thesize of the portions dispensed and employ relatively complex andexpensive control and programming techniques.

A variety of devices have been used in the past to indicate the absenceof fluid, reverse fluid flow or some predetermined point just prior tothe absence of fluid in various systems. Such devices can comprise anyof a number of systems including float systems, optical systems,conductive or resistive systems, ultrasonic systems, pneumatic systems,weight sensing systems, mechanicalsystems and the like. Most suchdevices suffer from one or more undesirable features which includenecessity for precise orientation, high cost, complexity, erroneoussignal indications, lack of adaptability, unacceptable free movingparts, complicated cross wall linkages and others. Thus, there aredifficulties in adopting a reverse flow sensor in hot chocolatedispensers to indicate an out-of-syrup condition which would activate adispenser shut off, or give some other indication to the user. Yet, itis desirable to have an out-of-syrup condition indicated to a hotchocolate dispenser operator in order to prevent less than apredetermined ratio of syrup to water being dispensed from a dispenser.

One object of this invention is to provide a hot chocolate dispenserwhich is extremely simple to operate.

and sensitive to unwanted reverse flow.

Still another object of this invention is to provide a sensor inaccordance with the preceding objects which is highly useful to indicatean out-of-syrup condition in hot chocolate dispensers of this invention.

Still another object of this invention is to provide a reverse flowsensor in accordance with the preceding objects which is highly compact,relatively low in cost, easily reset after shut down, capable ofoperating with out auxiliary equipment and does not require frequentadjustments in use.

Still another object of this invention is to provide a reverse flowsensor in accordance with the preceding objects which is .unaffected bychanges in physical properties of chocolate syrups, has an easilydiscernible signal output, is relatively insensitive to damage byhandling and is capable of being sanitized while in place in a hotchocolate dispenser.

To accomplish these and other objects, the hot chocolate dispenser ofthis invention includes a syrup and water control assembly which incooperation with the water and syrup sources preserves a fixed ratiobetween water and syrup for large and small portions. A syrup circuitwhich includes the control assembly also includes a positivedisplacement pump that moves a constant volume of syrup in the systemduring each cycle. The assembly for small portions diverts a part of theoutput of the positive displacement pump and simultaneously reduces thetotal water flow, and by means of a single control knob the portionselection is made.

The reverse flow sensor comprises a check valve slider carrying a magnetand positioned in operative relationship to a magnet sensitive means foropening and closing an electrical circuit. Movement of the magnet alongwith the slider in response to fluid pressures, actuates the meansresponsive to the magnet to indicate an out-of-syrup or reverse flowcondition.

Typically two-portion hot chocolate dispensers are designed to give sixand eight ounce servings. The flavor concentrates now used for bestresults employ a 5:1 ratio of water to syrup. In accordance with thepresent invention the positive displacement pump in the syrup circuitmoves the full volume of syrup required'for the larger portion, and whena smaller portion is to be served, the syrup and water control assemblydivertsa portion of that syrup so that it does not reach the dischargenozzle of the machine.

In the drawing one embodiment of this invention is illustrated, wherein:

FIG. 1 is a perspective view of a hot chocolate dispenser constructed inaccordance with this invention;

FIG. 2 is a perspective view, partially broken away, of the dispensershown in FIG. 1 with only the syrup circuit being illustrated forpurpose of clarity;

FIG. 3 is a side view of the dispenser shown in FIG. 1 with only thewater circuit shown;

FIG. 4 is an enlarged cross sectional view of the syrup and watercontrol assembly;

FIG. 5 is a schematic diagram of the electrical control circuit of thepresent invention;

FIG. 6 is a cross sectional view through a preferred embodiment of areverse flow sensor in accordance with the present invention;

FIG. 7 is a cross sectional view of the slider thereof taken along line7-7 of FIG. 6;

FIG. 7A is a bottom view thereof;

FIG. 8 is a schematic diagram of the electrical control circuitutilizing the sensor of FIG. 6;

FIG. 9 is a cross sectional view through the center of an alternateembodiment of a reverse flow sensor in accordance with the presentinvention;

FIG. 10 is a schematic diagram of the electrical control circuitutilizing the sensor of FIG. 9;

FIG. 11 is a cross sectional view through the center of an alternateembodiment of a syrup supply can and associated structure for use in thebeverage dispenser of FIG. 1; and

FIG. 12 is a cross sectional view through a modified portion of a syrupand water control assembly showing a modification of the assembly shownin FIG. 4.

The beverage dispenser of this invention is designed to serve twodifferent size portions of hot chocolate. Before the machine isactuated, the selection is made by means of a control knob provided onthe front panel of the machine. The beverage dispenser shown includes ahousing 10 which contains a syrup delivery circuit 12 (FIG. 2), a waterdelivery circuit 14 (FIG. 3), and an electrical control circuit 16 (FIG.5). The housing 10 has a drip tray 18 attached to the bottom of itsfront wall and a mixing assembly 20 mounted above it. The assembly 20 isshown and described in detail in US. Pat. No. 3,568,887 entitled HOTBEVERAGE DIS- PENSER. Included as part of the syrup circuit and thewater circuit is a reserve cylinder and water control assembly 22 (FIG.4) attached on the inside of the housing 10 to the front panel 24.

The syrup circuit 12 is shown in FIG. 2, isolated both from theelectrical circuit and the water circuit for clarity. Chocolate syrupcan 30 is mounted on shelf 32 forming part of the housing 10 and iscovered by the hood 34 (see FIG. 1) forming part of the housing; A diptube 36 carried by the can cover 38 extends downwardly into the can tothe region of the can bottom, and the top of the dip tube is connectedby means of a quick connect fitting and check valve assembly 40 to duct42 in turn connected to the cylinder 44 of positive displacement pump 45in the syrup circuit.

The pump 45 includes a piston 46 movable in the cylinder 44 and carriedon the end of piston rod 48 in turn operated by crank 50 connected tothe rotating cam 52 driven by the cam motor 54. As the cam 52 rotates,the crank 50 moves the piston 46 up and down in the cylinder 44 througheach revolution. The pump 45 is shown in the drawing to be mounted onpartition 56 in housing 10.

The outlet duct 58 of pump 45 is connectedto the reserve cylinder andwater control assembly 22 whose syrup outlet 60 in turn extends out ofthe housing to the mixing chamber 20. The discharge duct 60 carries acheck valve 62 at its discharge end to prevent air or other matter fromentering the duct 60 and fouling or contaminating the syrup circuit andfor cutting off flow at the end of the pump cycle to eliminateafter-drip.

In FIG. 4 the syrup or reserve cylinder and water control assembly isshown in detail. The assembly 22 in cludes a metering chamber 64controlled by sliding piston 66. The chamber 64 serves as a reservoirfor the system so as to permit the syrup circuit to discharge either oneof two selected volumes of syrup. When the reserve piston 66 is lockedin the position shown in FIG. 4 the same volume of syrup drawn intocylinder 44 of pump 45 during the down stroke of the piston 46 will beexpelled through the check valve 62 when the piston rises during itsdischarge stroke. A recess 68 cut in the face of the reserve piston 66allows the syrup to flow from the duct 58 to the discharge duct 60during the positive stroke of the pump. The pump acts as a positivedisplacement pump, and the amount of the syrup displaced in the systemwill be exactly equal to the volume of displacement of the piston in acylinder.

The push rod 70 is provided to lock the reserve piston 66 in place sothat the amount of syrup discharged exactly equals the amount displacedby the pump 45. The push rod 70 carries a pair of ears 74' that aredisposed in slots 76 adjacent chamber 64. When the push rod is moved tothe right so that its end 78 engages the inner face 80 of the reservepiston 66, the ears 74 will just clear the ends of the slots 76, and thepush rod may be rotated so as to misalign the ears with the slots. Whenthis is done, the ears 74 will bear against the face 82 of flange 84 ofwatercontrol housing 72 so as to retain the rod in its depressedposition. Consequently the reserve piston 66 will not be permitted tomove to the left as shown in the figure, and the chamber 64 will notcollect any of the syrup displaced by the pump 45. However, when the rod70 is in the position shown in FIG. 4 so that it does not interfere withmovement of the reserve piston 66, it will be appreciated that when thepiston 46 of the pump displaces syrup from its cylinder, a portion ofthat syrup will be allowed to collect in the chamber 64 as the reservepiston 66 moves to the left. So long as the volume displaced by pump 45exceeds the maximum volume of the chamber 64, the difference between thevolumes will be dispensed through check valve 62 of outlet duct 60.Whatever syrup collects in the chamber 64 due to displacement of thereserve piston 66 will be recollected in the cylinder 44 during thereturn stroke of piston 46. Thus by disabling the reserve piston 66 sothat it cannot move, the quantity dispensed through the check valve 62will equal the quantity of syrup displaced by the pump 45. If thereserve piston 66 is allowed to move to the left so as to expand thechamber 64, then the amount of syrup discharged through the check valve62 will be equal to the quantity of syrup displaced by the pump 45 minusthat which is allowed to collect in the expanded chamber 64. Knob 86secured to the front end of the push rod 70 and extending out of thehousing at the front panel 24 enables an operator to select the amountof syrup to be discharged by the syrup circuit 12.

The water circuit 14 shown in FIG. 3 is very similar to that shown inUS. Pat. No. 3,568,887 supra, and therefore it will be described onlybriefly. The water circuit includes heating tank supported on the bottomof the housing 10.- The heating tank 100 is fed water through inlet duct102 solenoid valve 104, reserve cylinder and water Control assembly 22,and filler duct 106. Heated wateris discharged from tank 100 throughoutlet 108 which is connected through an expansion chamber 110 todischarge duct 112. An overflow line 114 is connected to the expansionchamber 110 and is shown to have a discharge port 116 immediately abovedrip tray 18. In order to discharge water from the tank 100, the watermust be displaced from the top by water fed into it through duct 106.This is in turn controlled by the solenoid valve 104. It will be notedthat the solenoid valve 104 is on the cold water side of the tank, whicheffectively prolongs the life of the rubber parts of the valve.

The reserve cylinder and water control assembly 22 not only serves tometer the amount of syrup discharged into the mixing chamber 20, butalso serves to meter the quantity of water displaced from the tank 100.Reference again is made to FIG. 4 to illustrate this function. In thatfigure water control housing 72 is shown to include a main water inlet118, a water outlet 120, and a secondary water inlet 122. Secondarywater inlet 122 is connected to the outlet 120 through a valve 124defined by the conical configuration of push rod 70 which cooperateswith the conical seat 126 in housing 72. When the valve is closed asillustrated in FIG. 4, no water is allowed to pass from the secondaryinlet 122 to outlet 120, and the only water allowed to flow through thesystem is that which enters inlet 118. The push rod 70 does notinterfere with the flow of water between the inlet 118 and the outlet120. In FIG. 3 the solenoid valve 104 in the water circuit is shown tobe connected through flow control 128 to the primary inlet 118 of thereserve cylinder and water control assembly 22, and the outlet of thesolenoid 104 is also shown connected by means of duct 130 to thesecondary inlet 122 of the housing 72. The flow control 128 is ofstandard design and the details form no part of this invention. Sufficeit to say that it includes a needle valve adjustable through the frontof the housing as it extends out panel 24, and it also includes a rubberannular gasket which varies in size under pressure so as to provideconstant flow regardless of line pressure. A flow control 129 located atthe inlet 122 performs the same function, but it is not adjustable.

To discharge water through duct 112 into the mixing chamber 20, thesolenoid valve 104 is opened, and the amount of water which flowsthrough the assembly 22 into the tank 100 exactly equals the amount ofwater which is discharged through the duct 112 into the mixing chamber.The quantity of water fed to the tank 100 in a given interval dependsupon the position of push rod 70. When the push rod is moved to theright from the position shown in FIG. 4 so as to disable the reservepiston 66, the valve 124 .unseats so as to allow secondary water as wellas primary water to flow through the water control housing 72. However,when push rod 70 is in the position shown in FIG. 4,-the valve 124 isclosed and only primary water flows. Thus, when a greater quantity ofsyrup is discharged through assembly 22 caused by the disabling ofreserve piston 66, a greater quantity of water. also discharges into themixing chamber. This is explained more fully in connection with theoperation of the machine below.

Push rod 70 carries an O-ring 132 to prevent water from entering thechamber 64. Another O-ring 134 is carried on the push rod adjacent itsother end and prevents water from leaking about the rod in the directionof the knob 86.

The mixing chamber 20 identical to that shown in US. Pat. No. 3,568,887supra, contains a mixing impeller 136 driven by a whipper motor 138. Thewhipper motor 138, gear motor 54, and solenoid valve 104 are alloperated by the control circuit shown in FIG. 5.

Connected across lines L1 and L-2 in the control circuit is heater 140of tank 100, which is controlled by thermostat'l42 that may be set tocontrol water temperature. A pilot light 144 is also connected acrossthe line, which indicates when the machine is on. The machine is tumedon by switch 146.

To dispense hot chocolate from the machine. starter switch 148 isdepressed, which immediately closes the circuit for gear motor 54, andthe motor starts to run and rotates cam 52. The crank 50 moves thepiston 46 upwardly in the cylinder to discharge syrup from the syrupcircuit. Simultaneously a pair of microswitches 150 and 152 shown inFIG. 5 move from their normally open position to the closed position.When the starter switch 148 is closed, it temporarily completes thecircuit for the motor 138, and switch 150 immediately thereafter isclosed by the cam driven by motor 54 so as to connect the whipper motor138 across the line through switch 154 forming part of the sanitizingswitch assembly 156 described below and thus the whipper motor continuesto run after the switch 148 is released. As the gear motor 54 turns, thewhipper motor and solenoid valve circuits are both closed through theswitches 150 and 152 controlled by the cam 52, and water is dischargedthrough the water circuit 14 into the mixing chamber 20 and chocolatesyrup is discharged into the mixing chamber through the syrup circuit12. When the gear cam 52 turns through 180, the syrup feed willdiscontinue, and the piston 46 will move downwardly in the pump 45 torefill the cylinder. Typically, the gear motor 54 may rotate at 6 rpm,and one revolution or cycle of the cam 52 takes 10 seconds. In thisarrangement discharge of syrup from the syrup circuit consumes one-halfcycle or 5 seconds. The remaining 5 seconds of the cycle is consumed inrefilling the pump 45. The cam 52 which operates the switch 152 isdesigned to reopen the switch 152 after 5 seconds of the cycle, so thatwater flow is limited to that duration. During the remaining 5 secondsof the cycle, the whipper motor 138 continues to operate to provide anafter whip which is described fully in US. Pat. No. 3,568,887 supra.When the cam completes its cycle, the normally open switch 150 reopens.The foregoing description of the control circuit cycle applies equallyto situations where the dispenser is discharging either a small or alarge portion. That is, the lO-second cycle described applies whether ornot the push rod 70 is in the depressed or released position.

The control circuit of FIG. 5 permits hot water to be drawn from thedispenser without syrup. Switch 160 is provided for that purpose. Whenthat switch is closed, the solenoid valve 104 is connected across thelines L1 and L2, and it is energized without energizing the motors 54and 138 which drive the whipper and the cam. So long as the switch 160is closed the hot water will discharge from the machine.

As is evident above, with the assembly 22 an operator may select betweentwo sizes of drinks which may be dispensed by the machine. Typically thetwo sizes are six and eight ounces. A conventional chocolate syrup tohot water ratio is 1:5, and therefore in a 6 ounce drink, one ounce ofsyrup is mixed with ounces of water. To preserve the ratio, in an 8ounce drink, 1.33 ounces of syrup are mixed with 6.67 ounces of water.In the machine described, the pump 45 is designed to deliver 1.33 fluidounces of chocolate in the pump cycle. It will be understood that thisquantity may be varied by changing the length of the crank arm 50established by the cam 52. The capacity of the chamber 64 in theassembly 22 is 0.33 fluid ounces of syrup. Therefore, if the push rod 70is in its depressed position barring operation of the reserve piston 66,1.33 ounces of chocolate will be dispensed from the pump 44 through thesystem into the mixing chamber 20. If on the other hand the reservepiston is allowed to move in response to operation of the pump 45, ofthe 1.33 ounces displaced by the pump, 0.33 ounces will be captured inthe expansion chamber 64 so that only one ounce of chocolate will bedischarged into the mixing chamber 20. As for the water circuit, if thestem 70 is depressed to disable the reserve piston, the secondary waterinlet 122 is open so as to allow 1.67 ounces of water to flow in 4seconds through the water control housing to the discharge por 120 andinto the mixing chamber 20. The water circuit is designed also to pump 5ounces of water through inlet 118 of the water control housing and intothe mixing chamber during the 4 second operation of the solenoid valve.Consequently with the push rod depressed, 1.33 ounces of chocolate aremixed with 6.67 ounces of water, while with the push rod in its outerposition, 1 ounce of chocolate is discharged with 5 ounces of water.

A desirable feature of any consumable beverage dispenser is that it becapable of being cleaned and sanitized easily and effectively. Mostdispensers require some dismantling of the flavor concentrate flowcircuit with subsequent sanitizing by immersing and washing in asanitizing solution. This dispenser however, may be sanitized veryeasily as follows: the main on-off switch 146 is turned off, thechocolate syrup container 30 is replaced by a container of hotsanitizing solution, and an empty container is placed beneath the mixingchamber nozzle 21. By throwing the sanitizing switch 156 to the onposition (opposite to that illustrated), the gear motor 54 rotates andthe hot water solution is fed through the syrup circuit. By allowing thesolution to run through the machine for perhaps 3 minutes allowingsolution to remain in the syrup circuit for an additional minute or two,and then again flushing the system, the solution will totally clean thesyrup circuit of all residual chocolate. By this means all of theinternal parts in contact with the syrup are cleansed, including thepump and reserve system, check valves and associated transport tubing.Thus this operation may be carried out without dismantling the machineother than the chocolate syrup container itself.

Turning now to FIG. 12 a modification of the sliding piston arrangementwithin the reserve cylinder and water control assembly 22 is shown. Inthis modification, the reserve cylinder and water control assembly areidentical to that described with respect to FIG. 4 except that thesliding piston 66 and its associated O- ring type gasket 66A is replacedwith a diaphragm piston member indicated generally at 200. The diaphragmpiston member comprises a rubber or other resilient plastic diaphragm201 mounted in the walls of the metering chamber or reservoir 64 byclamps 202. A central portion of the diaphragm 201 defines a circularflat area 203 to which is attached a piston head 204. The

piston head 204 is not connected to the end of push rod but contacts theend of push rod 70 in the furthest extremity of travel to left of thehead 204. The head 204 is preferably of a rigid plastic in disc formalthough other rigid materials can be used. The push rod 70 and itsassociated spring 70A operate in exactly the same manner as describedwith respect to the embodiment of FIG. 4. Thus spring 70A acts to holdthe push rod 70 in its withdrawn position (i.e., small volume position)to thereby block the secondary water path and reduce the volume of waterdispensed in a single cycle. The full lines of the diaphragm shown inFIG. 12 indicate the small volume drink position of the piston head 204and associated diaphragm. Movement to the right to the dotted lineposition shown in FIG. 12 indicates the large volume position of thepiston head 204 and diaphragm portion 201. Thus, the piston diaphragmarrangement of FIG. .12 operates as does the sliding piston 66 and isactuated in the same manner within the reserve cylinder and watercontrol assembly 22. However, since the diaphragm is continuous, thereis no chance of leakage through a gasket seal such as gasket 66A of FIG.4.

With reference now to FIG. 11, an alternate syrup supply structure isshown which is more fully described in copending application Ser. No.36,863 filed May 13, 1970 entitled LIQUID DISPENSING SYSTEM (nowabandoned) which application is incorporated by reference herein. Asdescribed in that application, the syrup supply portion of the dispensershown in FIG. 2 is modified as shown in FIG. 11 to obtain an improvedfluid hopper. In the embodiment of FIG. 11, the duct 42 passes upwardlyto the can 30 which is supported on the shelf 32 forming part of thehousing 10. The can 30 is connected by means of the duct 42 to thecylinder 44 of the pump. The can 30 has an opened bottom end 260. Thecan can be opened by a common electric or manual knurled wheel drive canopener or any other convenient tool. The opened end 260 of the can iscovered by a lid 262 having a closure wall 264 and an upwardly extendingperipheral skirt 266 which lies about the outer surface of the lower endof the cylindrical wall of the can. The lid 262 is preferably formed ofa resilient plastic material. A pair of tabs 268 extend from oppositesides of the top edge of the skirt to facilitate removal andinstallation of the lid 262.

A dispensing nipple 270 in the formof a duck bill check is formed at thecenter of the closure wall 264. The nipple 270 has a generallycylindrical body 272 which terminates in converging walls 274 and adownwardly extending central flap 276. The flap is cut as shown at 278but no material is removed so that no stresses are applied to the nippleand the flap sides are engaged to close the cut or slit and prevent flowthrough the nipple. I

A second nipple 280.in the form-of a duck bill check extends upwardlyfrom the closure wall 264 of the lid adjacent its periphery and has acylindrical wall 282, converging wall 284 and flap 286 with a slit 288that may be identical to the corresponding parts of the nipple 270.

A rigid backup plate 290 lies within the closure wall 264 of the lid 262and has an opening 292 through 9 which the nipple 280 extends into theinterior of the can 30. The periphery 294 of the backup plate 290 restson the bead 261 of the can 30 to provide stiffness for the lid 262 andperform other functions. The backup plate 290 also carries as anintegral part thereof a cylindrical sleeve 296 which fits withinthenipple 270 and supports it in the position shown. The sleeve 296 has abead 298 on its outer surface, which stretches the nipple 270 and formsa corresponding bead 300 on the nipple wall 272.

A check housing 302 is mounted on the platform 32 of thedispenserhousing l and its lower end 304 of reduced diameter isconnected to the end of the duct 42 which carries the syrup from the can30 to the pump. The check housing 302 is sized to receive the nipple 270when supported on the sleeve 296, and a circular seat 306 is provided onthe inner surface of the housing 302 so as to receive the bead 300formed in the nipple 270 by the corresponding bead 298 on the sleeve296.

In operation, the nipples 270 and 280 perform two separate butinterrelated functions. By making the slits 278 and 288 sharp andcleanly defined slices without removing material, thin hairline slitsare formed which will close by elastomeric memory once the slittingknife or tool used to form it is removed. Thus, each nipple serves as acheck valve which will not leak liquid during the normal gravity headconditions. When the lid 262 is used in the dispenser of FIGS. 1-5,check valve 40 can be eliminated since the nipple 270 functions as abackflow prevention check valve to stop all substantial backflow in thesystem.

The nipple 270 serves an a unidirectional flow check valve in the syrupinlet to the pump. Nipple 280 allows air intake into the can to relievepressure differences. Thus, the nipples 270 and 280 keep the system inpressure equilibrium during the dispensing cycle as more fully describedin the above-noted copending US. patent application Ser. No. 36,863.

As described above, with either the syrup supply of FIG. 2 or that ofFIG. 11, the drink dispense button results in water and syrup beingdelivered to a mixing chamber in proper ratio in amount for apreset sizedrink. For example, when using the syrup supply of FIG. 11, this may bea 6 fluid ounce drink comprising 1 fluid ounce of syrup and fluid ouncesof water. Under these conditions, a 2% size syrup can givesapproximately 26 drinks before emptying the can, excluding the roughly 4fluid ounces required to fill the syrup circuit, while a No. 10 size canwould give approximately 96 drinks.

Using the dispenser as described above, the advantages described aboveare obtained; however, the syrup can be exhausted from the syrupcontainer before an operator is alerted to the fact that a weak drink isabout to be dispensed. Under most conditions, the dispenser is installedin so-called fast service restaurants where little time or attention isallowed to check the amount of syrup left in the can. Since the syruplevel is not readily observable, it is common for the can and syrupcircuits to be exhausted of syrup without the knowledge of the operater.For this reason, it is preferred to have a device which alerts theoperator to the instant in time when the can is just becoming empty butthe syrup circuit is still virtually full.

As noted above, the flow of syrup in the syrup circuit is only in onedirection and is governed by-the orientation of the check valves such as40 and 62 or 270 in place of 40. However, in one condition there is aslight reversal of syrup flow which occurs when the syrup reservoir doesnot contain enough syrup to fill the syrup circuit and air has beendrawn into the syrup circuit. During the pump discharge stroke, pressureis developed in the syrup transport tubing which causes flow anddischarge of syrup through the outlet check valve 60. During thispressure period the syrup in the transport tubing leading to the pumpfrom the syrup reservoir is stationary. However, if a small amount ofair is drawn into the syrup line between the syrup reservoir and pump,this column of air becomes compressed during the pump discharge strokeand a small amount of reverse flow of the syrup results. This smallreverse flow is utilized in the reverse flow indicator of this inventionthe preferred embodiment of which is illustrated in FIGS. 6, 7, 7A and 8at 400.

The sensor 400 has a hollow cylindrical housing formed of upper andlower halves 401 and 402 joined midway in their cylindrical wall at 403with upper and lower duct fitting ends 404 and 405. Flow through thesensor is normally in the direction of arrow 419 when the sensor isconnected in duct 42 preferably between the first check valve such as 40or 270 and the cylinder The inner configuration of the housing is in theform of an upper cylindrical section or chamber 406 which houses anupper umbrella-shaped portion 407 of a check valve slider 408. A lower,smaller diameter cylindrical section 409 houses a cylindrical magnet410. A bottom cylindrical section 411 of still smaller diameter houses aduck bill 414 of the slider 408.

The magnet 410 is a permanent magnet whose dimensions are such that itsouter cylindrical surface is slightly smaller than the housing section409 and its inner diametric surface is sized to coincide with theoutside diameter of the cylindrical portion of the slider which ispreferably elastomeric. The entire slider is preferably formed of arubber or other elasotmeric or resilient material. A flat, upper end ofthe magnet is preferably dimensioned to underlie a flat portion 413 ofthe slider. The longitudinal length of the magnet provides guidingof themagnet in the housing through its normal distance of operating travel.

The slider 408 acts as a check valve and is of generally cylindricalshape having an internal, cylindrical, syrup passageway which convergesto a rectangular shape of narrow clearance 414 opened at the end by aslit 415 and is thus in the general shape of a duck bill nipple such as280. The cylindrical portion of the slider coincides with thelongitudinal extent of the magnet while the rectangular portion extendsbeyond the magnet into the lower cylindrical section of the housing. Theupper, umbrella-shaped slider portion of the check valve slider has anouter diameter such that it nonnally grips the inside diameter of thecylindrical portion 406 and provides a slight degree of resistance tomovement. The magnet and slider are mechanically linked together so asto move together as a single unit.

A magnetic reed switch 420 having electrical leads 421 and 423 ispositioned in operative association with the magnet 410. As known in theart, the reed switch has an evacuated and sealed glass envelope 422 withmetallic contacts 424 mounted on spring strips and constituting anelectrical, signal output portion of the sensor. The magneticsusceptibility of the spring strips is such that an influencing magneticfield of sufficient strength overcomes the biasing force of the springsand causes the contacts to close to complete a circuit. The

leads 421 and 423 can be interconnected to suitable electrical circuitryas will be described, as in the dispenser 10, to interrupt operation ofthe dispenser on proper demand. The position of the reed switch as shownin FIG. 6 is such that the magnet 410 holds the switch in its closedposition when the syrup container fully supplies the syrup circuit. Thereed switch opens upon movement of the magnet in an upward directionfrom that shown in FIG. 6.

The sensor 400 is installed in the syrup line such as 42 between thesyrup reservoir and the pump and when the syrup circuit is full, thesensor remains in the posi tion shown in FIG. 6. Unidirectional flow ofsyrup in the direction of arrow 419 results in a pressure differentialacross the slit of the check valveslider which keeps the movable portionof the sensor in position since the only path for syrup flow is throughthe area of the slit.

Preferably the sensor 400 is far enough away from the syrup reservoir topermit an optimum amount of air to enter the syrup reservoirto permit anoptimum amount of air to enter the syrup circuit upon exhaustion of thesyrup reservoir and thus result in a measurable amount of compression ofthe air and reverse flow of syrup during the pump stroke without airgoing beyond the sensor in the syrup circuit.

Once the syrup reservoir has been drained of syrup,

on the next refill stroke of the pump, air is drawn into.

the syrup circuit. This column of air is of sufficient size to becompressed or displaced during the pump stroke, yet, not so large as toexhaust the system of syrup. The air must be upstream of the sensor topermit the syrup in the pump to reverse flow in the direction of thesensor. However, the duck bill prevents reverse flow through the slit415.

In one application, the sensor 400 is located right at the inlet to thepump thus resulting in approximately 12 inches of inch inside diameter,reinforced flexible tubing between the sensor and the syrup reservoir.Typically, about 4 inches of this tubing is filled with air during thepump refill stroke at the instant the syrup reservoir is exhausted ofsyrup. This represents approximately 0.44-cubic inches or A fluid ounce.During the pressure stroke the system pressure builds up to as high aspsig, resulting in this column of air being compressed from 4 inches inlength of tubing to approximately 1.3 inches or a resultant reversemovement of syrup of 2.7 inches. Since the sensor slider 408 need moveonly approximately inch to deactivate the reed switch, adequate reversemovement of the slider can easily be achieved.

Once reverse flow of the syrup begins, the slit in the sensor valvecloses tightly due to the pressure differential. This syrup pressurethen acts against the projected area of the magnet and check valvethereby causing the slider and magnet to move upwardly.

The umbrella section at the top of the check valve slider 408 serves twopurposes. First, it prevents air from bypassing around the check valveduring reverse flow and second it serves to hold the magnet in place inthe raised position by virtue of the friction resulting from the slightinterference between the rubber or elastomeric material of the sliderand the housing.

The associated electric circuitry for the sensor 400 is illustrated inFIG. 8 where the circuit 450 is basically identical to the circuitdescribed with regard to FIG. 5 with the additional reed switchcomponent added along with a relay 451 and an out-of-syrup light 452connected as shown. This circuitry assures that continuous operation ofthe dispenser is interrupted whenever the reed contacts are open.Voltage to the pump drive or gear motor 54 is dependent upon acontinuous circuit through the reed switch. To initiate a drink dispensecycle, the push start button 146 is suppressed and released. Themomentary contact of the normally opened switch starts the gear motorwhich through a cam arrangement depresses the button of the cam operatedmicroswitch which maintains the voltage to the gear motor 54 until themotor output shaft has made one revolution. At this point, the camdisengages the switch and the motor stops. This constitutes one drinkdispense cycle. Whenever air is drawn into the syrup circuit, thereverse travel of the sensor slider 408 causes the reed switch to open,thus stopping the gear motor 54 in midpump stroke. Depressing the pushstart button will not restart the cycle until the reed switch is againclosed.

A neon bulb 452 with high resistance is located in parallel with thereed switch. During periods when the reed switch contacts are closed,the current flow is principally through the reed switch, thus, there isinsufficient voltage to the neon bulb 452 to activate it due to the highresistance. When the reed switch contacts are opened, current flow isthrough the neon bulb and the resistance is sufficiently high to dropthe voltage to the relay coil of relay 51 to a point where it will notoperate. In this way a visual warning is provided which automaticallyindicates when the dispenser is out of syrup. The out-of-syrup light 452can be located on the front panel of the dispenser.

The electromagnetic relay 451 which is preferably a single pole, singlethrow electromagnetic relay is used between the reed switch and the gearmotor to isolate the current load of the motor from the reedcontacts.This eliminates the tendency for arcing to take place at the reed switchcontacts thus giving prolonged switch life.

When the dispenser is stopped due to movement of the slider 408, theempty syrup reservoir is replaced with a full one and the fill orsanitizer switch 156 is engaged. This switch bypasses all othercircuitry and operates the gear motor independently. Since the gearmotor (pump) 54 is stopped on midpump stroke it completes the pumpstroke and proceeds to a refill stroke, thus drawing new syrup into thesyrup circuit. This results in entrapped air being drawn along with thesyrup, through the sensor and into the pump where it can no longeraffect the sensor. Ordinarily this takes just the remaining cycle of thepump to transfer the air and reset the magnet which re-engages the reedswitch in the closed position. At this point, the light 452 goes verseflow sensor is ideally suited to many applications including use in thehot drink dispensers of this invention. The sensor is capable of beingsanitized without dismantling. Thus, the magnet is inert and nonporousand the check valve can be formulated of FDA approved plastics and thelike enabling easy cleaning with hot water during periodic sanitizing ofthe hot drink dispenser. The sensor is highly reliable and accurate andrelatively insensitive to damage by handling since the magnet and checkvalve slider are not free to move within the sensor unless influenced bythe flow of syrup avoiding damage or displacement due to dropping orjarring in shipment or use. The signal output from the reed switch iseasily discernible to the naked eye from the outside of the machine.Changes in physical properties of the chocolate syrups used due toatmospheric changes and the like do not affect the sensor since the flowcharacteristics which activate the sensor are not thereby affected. Noancillary equipment is necessary in the circuitry of the hot drinkdispensers and no field changes or adjustments need be made. Moreover,the sensor is easily and simply reset after shut down as describedabove. The sensor is further low in cost, compact and integral with thedispensers of this invention.

In an alternative sensor system shown in FIGS. 9 and 10, a sensor 500 isused with all parts being identical to corresponding numbered parts ofthe sensor of FIG. 6.

The only difference is that the check valve slider does not have theumbrella-shaped section at its upper end but rather merely the flatportion 413 completely overlying the magnet and having an outer diameterspaced from the inner diameter of the cylindrical chamber 501. Thesystem shown in FIGS. 9 and 10 allows the magnet to free move in thestraight cylindrical wall of the valve housing. Thus, the magnet is notheld in position once it has been raised by reverse flow, but, isallowed to seek a reset position both by free settling and influence ofrestored normal flow.

In the embodiment of FIG. 9, gravity is used to return the slider to itslowermost position when the back pressure is released. However, ifdesired, a low force return spring can be used in chamber 510 to biasthe slider to its lowermost or seated position. Because of the close fitof the rim 413 and the cylindrical chamber 510 only an extremely smallinsignificant amount of syrup leakage occurs past the check valve sliderduring compression of the air.

The electrical circuitry is slightly modified over that shown in FIG. 8in that, in palce of a single pole, single throw electromagnetic relayused in FIG. 8, a double pole, double throw relay 460 is used. Thedouble pole, double throw relay 460 acts as a holding relay, maintainingthe pump circuit inoperative regardless of whether the reed switch isclosed or opened once it has been opened by one backflow pulse andupward movement of. the magnet.

The circuit of FIG. 10 functions as follows: power to energize the relaycoil of relay 460 comes from the output side (common) of a cam operatedgear motor switch 461 (B to 4) or directly from the power input (D to 2)depending upon whether the reed switch is closed and sequence of eventsleading up to the contacts closing. On initial start up of the hot drinkdispenser, the

sanitize switch 156 is engaged through the normally closedcontacts(upper half of the switch) which supplies input power to the gear motor54. As the gear motor rotates the drive cam, the cam operated gear motorswitch is closed and power is fed through B to the relay coil through 4.Since the magnet will be down due to free settling, the reed switch isclosed and the relay closes, making the circuit from D to 4. In thiscondition, the relay coil is maintained energized as long as the reedswitch is closed. At the same time, the power input through D-2-4 is fedto 3, thus establishing a working circuit to the push start switch I48and the lower half of the sanitize switch to permit normal operation ofthe dispenser on demand.

As previously described, the cam operated gear motor switch sustains theoperation of the gear motor through one revolution of the drive cam (onedrink dispense cycle) after the push start button has been released. Aslong as the reed switch is closed, the circuit remains and power isavailable for normal operation.

However, when air is drawn into the syrup circuit upon exhaustion of thereservoir, the magnet is raised as in the embodiment of FIG. 6 thuspermitting the reed switch contacts to open. When this happens, therelay coil circuit is opened and the relay contacts revert back to thenormally opened condition where they are maintained by a biased spring.Should the magnet settle back into place and reclose the reed switchcontacts, the relay coil cannot be. re-energized because the powercircuit from D is being maintained open.

A warning light 452 (out-of-syrup light) is used as in the embodiment ofFIG. 6 through the circuit D to neon bulb to 1 to 4 to B through the camoperated gear motor switch which is still made at the point where thegear motor is shut down at midcycle, then to F, through the gear motorto G. Because of the high resistance of the neon bulb, the voltage dropis sufficient to prevent the gear motor from running.

To restart the system with a replenished syrup reservoir, the procedureis basically the same as with the embodiment of FIG. 6. Engaging thesanitize switch runs the gear motor to refill the pump, thus removingthe air from the inlet tubing and simultaneously restoring the voltageto the relay coil thus resetting it for normal operation.

While the reverse flow sensors of this invention have been described inconnection with hot drink dispensers, the sensors can be used in anysystem which depends upon a preferred direction of flow of a gas orliqaid for normal. operation in which reverse flow is deemedunacceptable. Other systems in which the reverse flow sensor could beused include effluent treatment systems where it is undesirable foruntreated waste materials to contaminate treated effluents. Similar incarbonated water transfer systems, uncarbonated water being transportedin conventional copper pipe lines to a carbonating system can bemonitored by the sensors of this invention. A reverse flow indicator isimportant here to prevent backflow of carbonated water.

What is claimed is:

l. A reverse flow sensor comprising,

a housing having a chamber with an inlet and an outlet,

a magnet carried by a slider for movement within said chamber, saidslider having a passageway permitting all flow of fluid from said inlettherethrough in one direction and impeding fluid flow from saidresilient duck bill slit end and said first fluid flow passes outlet ina second direction so that fluid flow tothrough said cylindrical bodyout of said duck bill end, ward said second direction acts to move saidslider in said .second direction to block flow from said said duck billend providing for urging of said slider outlet to said inlet, in saidfirst direction during fluid flow therethrough and magnetic responsivemeans associated with said in said first direction and for urging ofsaid slider housing for reacting to movement of said slider. in saidsecond direction during fluid flow in said 2. A reverse flow sensor inaccordance with claim 1 second direction toward said slider. whereinsaid magnetic responsive means is a reed 4. A reverse flow sensor inaccordance with claim 3 switch responsive to movement of said magnet tomake wherein said slider carries an outwardly extending rim. and breakan electrical circuit. said chamber defining a wall with said rimengaging 3. A reverse flow sensor in accordance with claim 2 said wallin sliding frictional engagement therewith. wherein said slidercomprises a cylindrical body with a UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No. D ted NOVGmbGI Inventor(s) John A.Gardner, Jr. and Merle S. Brown It is certified that error appears inthe above-identified patent and thatvsaid Letters Patent are herebycorrected as shown below:

Column 7; line 26, change "por" to --port--.

Signed and Scaled this Tenth Day Of April I979 [SEAL] Arrest:

NALD mm! c. MASON D0 W BANNER Attestiug Oflicer Commissioner of Patentsand Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONpatent 3,851,127 Dated 26 November 1974 Inventor(s) John A. Gardner, Jr.and Merle S. Brown It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 7; line 26, change "por" to -port.

Tenth Day Of April 1979 [SEAL] Attest:

RUTH C. MASON DONALD W-. BANNER Arresting Ojficer Commissioner ofPatents and Trademarks

1. A reverse flow sensor comprising, a housing having a chamber with aninlet and an outlet, a magnet carried by a slider for movement withinsaid chamber, said slider having a passageway permitting all flow offluid from said inlet therethrough in one direction and impeding fluidflow from said outlet in a second direction so that fluid flow towardsaid second direction acts to move said slider in said second directionto block flow from said outlet to said inlet, and magnetic responsivemeans associated with said housing for reacting to movement of saidslider.
 2. A reverse flow sensor in accordance with claim 1 wherein saidmagnetic responsive means is a reed switch responsive to movement ofsaid magnet to make and break an electrical circuit.
 3. A reverse flowsensor in accordance with claim 2 wherein said slider comprises acylindrical body with a resilient duck bill slit end and said firstfluid flow passes through said cylindrical body out of said duck billend, said duck bill end providing for urging of said slider in saidfirst direction during fluid flow therethrough in said first directionand for urging of said slider in said second direction during fluid flowin said second direction toward said slider.
 4. A reverse flow sensor inaccordance with claim 3 wherein said slider carries an outwardlyextending rim, said chamber defining a wall with said rim engaging saidwall in sliding frictional engagement therewith.